1. Field of the Invention
This invention relates generally to medical devices, and more particularly concerns systems and methods for containing, aspirating and removing emboli from blood vessels, and especially during interventional procedures treatment of cerebral blood vessels such as carotid arteries to prevent emboli or debris from entering and occluding downstream blood vessels leading to the brain which may cause a stroke.
2. Description of Related Art
A variety of non-surgical interventional procedures have been developed for opening stenosed or occluded blood vessels in a patient caused by the build up of plaque or other substances on the walls of the blood vessel. Such procedures usually involve the percutaneous introduction of the interventional device into the lumen of the artery, usually through a catheter. One widely known and medically accepted procedure is balloon angioplasty in which an inflatable balloon is introduced within the stenosed region of the blood vessel to dilate the occluded vessel. The balloon catheter is initially inserted into the patient""s arterial system and is advanced and manipulated into the area of stenosis in the artery. The balloon is inflated to compress the plaque and press the vessel wall radially outward to increase the diameter of the blood vessel.
In another widely practiced procedure, the stenosis can be treated by placing a device known as a stent into the stenosed region to hold open and sometimes expand the segment of blood vessel or other arterial lumen. Stents are particularly useful in the treatment of repair of blood vessels after a stenosis has been compressed by percutaneous transluminal coronary angioplasty (PTCA), percutaneous transluminal angioplasty (PTA) or removal by atherectomy or other means. Stents are usually delivered in a compressed condition to the target site, and then are deployed at the target location into an expanded condition to support the vessel and help maintain it in an open position.
However, it has been found that stenting and angioplasty, particularly angioplasty of the cerebral vessels such as the carotid arteries, and saphenous vein graft (SVG) angioplasty, for treating veins grafted in bypass surgery, which can become diseased and bring an increased risk of generating emboli, pose risks of dislodging thrombus or friable plaque, and that such a thrombus or plaque that is dislodged during such a procedure can enter the bloodstream and subsequently migrate through the patient""s vasculature to sensitive organs such as the brain, where they may induce trauma. A thrombus or pieces of plaque material can be dislodged from a stenosis by expansion of the blood vessel being treated during a balloon angioplasty procedure and become released into the bloodstream. It has also been found that during deployment of a stent, it is possible for the stent to cut into the stenosis and shear off pieces of plaque which become embolic debris that can travel downstream and lodge in the patient""s vascular system.
Medical devices have been developed to attempt to deal with the problem created when debris or fragments enter the circulatory system following treatment utilizing any one of the above-identified procedures. One approach which has been attempted is the cutting of any debris into minute sizes which pose little chance of becoming occluded in major vessels within the patient""s vasculature. However, it is often difficult to control the size of the fragments which are formed, and the potential risk of vessel occlusion still exists, making such procedures in the carotid arteries a high-risk proposition.
Other techniques which have been developed to address the problem of removing embolic debris include the use of catheters with a vacuum source which provides temporary suction to remove embolic debris from the bloodstream. However, as mentioned above, there have been complications with such systems since the vacuum catheter may not always remove all of the embolic material from the bloodstream, and a powerful suction could cause problems to the patient""s vasculature.
Filters have been developed for trapping and preventing such embolic debris from flowing through the vasculature. Such filters are usually delivered in a collapsed configuration through the patient""s vasculature, and are then expanded once in place in the patient""s blood vessel to trap emboli. After emboli have been trapped, the filter can again be collapsed to remove the filter with any trapped emboli from the vessel. However, it has been found that trapped emboli can escape from such filters during the time that the filters are being collapsed and removed from the blood vessels. In other instances, the rate of blood percolating through the filtering material may be slower than the normal blood flow which can either cause the filtering material to tear or cause the filter to dislodge from the deployed position due to the build up of fluid pressure behind the filter. Moreover, should the filter become clogged with debris, there is a possibility that blood circulation past the clogged filter will be insufficient for the downstream vessels and organs. If a filter should become clogged when in use in the carotid arteries, blood flow could be diminished to the vessels leading to the brain. While the brain may be capable of functioning for a short period of time without sufficient blood flow, blood stoppage of more than thirty to forty seconds could cause the patient to experience a seizure. If the physician administering the procedure is unaware that the filtering device is clogged and that there is little or no blood flowing to the brain, the injury to the patient can be as devastating as if an emboli itself had caused blockage of the cerebral arteries.
One emboli containment system is known in which a treatment chamber is formed within a blood vessel by occlusion balloons provided on catheters on opposite sides of a stenotic lesion to prevent emboli migration during a treatment procedure, with irrigation and aspiration within the chamber through catheter pathways to remove emboli from the treatment chamber. However, that have been emboli partially dislodged and that are not removed by such irrigation and aspiration can later become free to migrate into the rest of the vasculature. It would be desirable for such a containment system to provide for turbulent flow of fluid within such a treatment chamber within the chamber, such as by jetting or streaming of the fluid in order to more thoroughly remove emboli from within the treatment chamber that may only have become partially dislodged during the treatment procedure.
What has been needed and has been heretofore unavailable are systems and methods for containing, aspirating and removing emboli that have been dislodge and partially dislodged from blood vessels in conjunction with such interventional procedures as stenting and balloon angioplasty of blood vessels, for minimizing the risk of embolic migration during and after the interventional procedures. The present invention meets these and other needs.
Briefly, and in general terms, the present invention provides for a system and method for isolation of a section of a blood vessel to prevent migration of emboli from the section during an interventional procedure, and subsequent flushing of the section to remove any emboli dislodged during the procedure. As used in the description of the present invention, the terms xe2x80x9cproximalxe2x80x9d and xe2x80x9cproximal directionxe2x80x9d are intended to mean moving away from the heart of a patient or out of the patient, and the terms xe2x80x9cdistalxe2x80x9d and xe2x80x9cdistal directionxe2x80x9d are intended to mean moving toward the heart of a patient, or into the patient. These definitions will apply with reference to body lumens and apparatus, such as catheters, guide wires, and stents.
Accordingly, in one presently preferred embodiment, the present invention provides for an emboli protection system, comprising a distal blocking balloon catheter and a proximal blocking balloon catheter for isolating a portion of a blood vessel to be treated by an interventional procedure to prevent migration of emboli into the rest of the vasculature. The distal blocking balloon catheter preferably includes a shaft with an inflatable balloon mounted on the shaft near the distal end of the catheter, the shaft having at least one lumen for a guide wire device and at least one lumen for fluid communication with the inflatable balloon. The proximal blocking balloon catheter similarly includes a shaft with an inflatable balloon mounted on the shaft near the distal end of the catheter, the shaft having at least one lumen for a guide wire device and at least one lumen for fluid communication with the inflatable balloon for inflation of the inflatable balloon. In one presently preferred embodiment, the shaft of the proximal blocking balloon catheter is open ended, and preferably includes at least one lumen for fluid communication with the interior lumen of the portion of the blood vessel being treated.
In one presently preferred embodiment, the inflatable balloon of the distal blocking balloon catheter has a surface defining a plurality of perforations facing the proximal end of the catheter, and the inflatable balloon of the proximal blocking balloon catheter also has a surface defining a plurality of perforations facing away from the proximal end of the proximal blocking balloon catheter, to allow fluid supplied to the inflatable balloons to exit the perforations and flush emboli in the isolated portion of the blood vessel through the open end of the proximal blocking balloon catheter and proximally through the fluid communication lumen of the proximal blocking balloon catheter. In one alternate embodiment, the distal blocking balloon catheter can be incorporated with an interventional therapeutic device such as an angioplasty balloon catheter. In another alternate embodiment, the distal and blocking proximal balloon catheters can be incorporated with an interventional therapeutic device such as an angioplasty balloon catheter. In another presently preferred alternate embodiment, the inflation balloons of either or both of the distal and blocking proximal balloon catheters can be non-perforated, with an additional lumen being provided in either or both of the distal and proximal blocking catheters to supply fluid to flush emboli from the isolated portion of the blood vessel.
The present invention also provides for a method for removing emboli during arteriovenous interventional procedures with such a dual balloon emboli protection system having a distal blocking balloon catheter and a proximal blocking balloon catheter, by the steps of placing a guide wire across a lesion (or desired site), threading the distal blocking balloon catheter over the guide wire and placing the balloon of the distal blocking balloon catheter distal to the lesion, threading an interventional device such as an angioplasty balloon catheter over the shaft of the distal blocking balloon catheter and positioning the interventional device at the lesion site, and threading the proximal blocking balloon catheter over the angioplasty device and placing the proximal blocking catheter""s balloon proximal to the lesion. The distal and proximal blocking balloons are then simultaneously inflated with an inflation fluid to block the portion of the blood vessel at both balloon sites, preferably with a low fluid pressure, such as 2-3 atm. for example, to isolate the lesion area from surrounding vasculature. When the balloons are perforated, the interventional device can be used to perform the angioplasty or similar interventional procedure, and then can be removed, without risking migration of emboli from the isolated portion of the blood vessel into the rest of the vasculature. The inflation fluid is then caused to stream out of the balloon perforations by increasing the pressure of the inflation fluid, which will, by a pressure differential that the fluid creates, flow through the open lumen of the proximal blocking balloon catheter and proximally through the proximal blocking balloon catheter out of the patient""s body. The flow pressure between the proximal and distal blocking balloons can also be varied to cause corresponding changes in the flow direction and/or create additional turbulence in order to flush out any remaining emboli.
In another presently preferred embodiment, a source of thrombolytic inflation fluid is provided that is connected in fluid communication with the inflatable balloons of the distal and proximal blocking catheters, and the thrombolytic inflation fluid is used to inflate the distal and proximal blocking balloons simultaneously with the thrombolytic inflation fluid to block the artery at both balloon sites, and to cause the thrombolytic fluid to stream out of the balloon perforations and flow through the central lumen of the proximal blocking catheter and out of the patient""s body, in order to break down and dissolve any thrombus and plaque in the isolated portion of the blood vessel through both the chemical effect of the drug and the streaming or jetting action of the fluid.
In an alternate preferred embodiment, the present invention provides for an emboli protection system for dissolving and removal of thrombus, stenotic or embolic material, that may be used during vascular interventional procedures or prior to such an interventional procedure for cleaning embolic material from a blood vessel, such as for cleaning a diseased saphenous vein graft prior to stenting of the graft. A blocking balloon catheter is provided, having a shaft with fixed distal and proximal inflatable balloons mounted near the distal end of the catheter. The blocking balloon catheter includes a shaft having one or more evacuation ports located between the distal and proximal balloons, and a lumen connected in fluid communication with the one or more evacuation ports for removing emboli through the proximal end of the catheter. The catheter also includes a lumen connected in fluid communication with the balloons for inflation of the balloons, and typically also have a lumen for a guide wire device. The distal and proximal balloons preferably have a surface defining a plurality of perforations, with the distal inflatable balloon having perforations facing the proximal end of the catheter, and the proximal balloon having perforations facing away from the proximal end of the catheter. Either or both of the inflatable balloons may also comprise a balloon-in-balloon configuration, with separate lumens being provided for inside and outside balloons. In such a balloon-in-balloon configuration, the inside balloon is non-perforated for use solely for inflation, while the outside balloon is provided with a surface defining a plurality of perforations, for drug delivery or flushing within an isolated portion of a blood vessel formed by inflation of the distal and proximal balloons, to allow simultaneous blocking of the blood vessel and flushing of emboli from the isolated portion of the blood vessel. In an alternate embodiment, one of the distal and proximal balloons may be non-perforated, and an additional lumen may be provided on the distal or proximal blocking catheter to supply a thrombolytic fluid to dissolve and remove thrombus, stenotic or other embolic material.
In the method of using the blocking balloon catheter with fixed distal and proximal inflatable balloons, the catheter is threaded over the guide wire to the desired location, and the distal and proximal balloons are preferably positioned on either side of the thrombotic or stenotic occlusion to be treated. Both balloons are then inflated to block the blood vessel, using a thrombolytic agent as the inflation fluid and under sufficient pressure to cause the thrombolytic inflation fluid to stream or jetting out of the perforations, to break down and dissolve the thrombus or plaque through both the chemical effect of the drug and the streaming or jetting action of the fluid ejected. Simultaneously, the drug and the thrombus, plaque or other embolic debris re evacuated from the site through the evacuation ports provided in the catheter.
In another presently preferred embodiment, the invention provides for triple balloon emboli protection system, comprising a guide wire or catheter shaft having a first, distal inflatable balloon mounted on the distal end of the guide wire or catheter shaft and at least one lumen for fluid communication with the distal balloon; a second, middle balloon mounted on the guide wire or catheter shaft proximal to the first inflatable balloon, such as for placing a stent, with the guide wire or catheter shaft having at least one lumen for fluid communication with the second, middle balloon; and a third inflatable balloon mounted on the guide wire or catheter shaft proximal to the second inflatable balloon, with the guide wire or catheter shaft having at least one lumen for fluid communication with the third balloon. The guide wire or catheter shaft is preferably provided with a fluid supply lumen with a port proximal to distal balloon to supply flushing fluid to flush emboli, and is preferably provided with an evacuation lumen with a port proximal to the second, middle balloon, for evacuation of flushing fluid and flushed emboli.
In a presently preferred method for using such a triple balloon emboli protection system for removing emboli during arteriovenous interventional procedures, such as angioplasty or placement of a stent, the guide wire is placed across a target site such as a lesion with the distal balloon distal to the lesion, the middle balloon at the site of the lesion, and the proximal balloon proximal to the lesion. The distal balloon is inflated with an inflation fluid to block the artery and isolate the lesion area from the surrounding vasculature, the middle balloon is inflated with an inflation fluid, such as to place a stent mounted on the middle balloon, and the proximal balloon is inflated to isolate the lesion area of the blood vessel from the rest of the vasculature. The middle balloon can then be deflated to release any emboli generated by placement of the stent, and can be reinflated and deflated to reduce the size of the lesion or stenosis at the target site, or to deploy or redeploy the stent evenly, or to a larger diameter. The proximal balloon can then be deflated, and fluid can be provided through the holes in the shaft proximal to the distal balloon for flushing emboli back through the artery for removal through a proximal connector device.
In another presently preferred embodiment, the invention provides for a single balloon emboli protection system, comprising a guide wire or catheter shaft having an inflatable balloon mounted on the distal end of the guide wire or catheter shaft and at least one lumen for fluid communication with the distal balloon. The proximal end of the shaft has a valve allowing for inflation and deflation of the balloon, which enables the balloon to remain dilated while the removable connector of a hemostatic valve, such as a rotating hemostatic valve, is gone. Infusion ports, holes or perforations are provided in the balloon facing the proximal end of the shaft, and are dimensioned to remain sealed until sufficient inflation fluid pressure is applied to the distal inflation balloon, in order to apply a pressure to the valve which will keep the valve closed when the connector is removed. The infusion holes are typically 0.001 to 0.002 inch in diameter. The action of the valve maintains a minimum pressure in the distal inflation balloon, allowing other devices to be introduced over the guide wire shaft during the procedure. Additional pressure can be provided to the distal inflation balloon to provide a flow of fluid through the infusion holes for providing a continuous flushing of the blood vessel proximal to the distal inflation balloon, which flows through the blood vessel, such as the external carotid artery, for example, back through a branching of the blood vessel, such as the carotid Y branching, for example, and performs aspiration by flushing emboli to another artery. The single balloon emboli protection system can be used in conjunction with currently compatible devices, such as balloon catheters, rapid exchange balloon catheters, stent delivery systems, guide wires, guiding catheters, angiographic catheters, and the like, and in particular can be used during vascular intervention, such as carotid artery angioplasty and stenting, in order to prevent stroke during carotid artery intervention.
In another presently preferred embodiment, the invention provides for an emboli protection system for isolating a portion of a blood vessel having a target site to be treated by an interventional procedure to prevent migration of emboli into the rest of the vasculature to permit perfusion and infusion of therapeutic drugs or fluid to the blood vessel being treated. The embolic protection comprises a blocking balloon catheter with a shaft having distal and proximal inflatable balloons, one or more guide wire lumens, and one or more lumens for fluid communication with the distal and proximal inflatable balloons. The shaft also includes one or more ports through the shaft proximal to the proximal balloon and one or more ports between the proximal and distal inflatable balloons, with the ports connected in fluid communication with the guide wire lumen to permit perfusion of blood to the isolated portion of the blood vessel through each the port between the proximal and distal blocking balloons. An inflation fluid supply is also connected in fluid communication with the distal and proximal inflatable balloons for supplying inflation fluid under pressure to the inflatable balloons under pressure for inflating the distal and proximal balloons in the blood vessel on either side of the target site to be treated, to isolate the selected portion of the blood vessel. In one presently preferred aspect, the guide wire lumen includes a distal opening, and a retractable guide wire device is disposed within the guide wire lumen, whereby the guide wire can be retracted from distal opening to permit perfusion of blood between the area of the blood vessel proximal to the proximal balloon to the area of the blood vessel distal to the distal balloon through the distal opening when the guide wire is retracted. In another presently preferred embodiment, a blocking balloon catheter is providing having a shaft with distal and proximal inflatable balloons, one or more guide wire lumens, one or more infusion lumens to allow infusion of therapeutic drugs or fluid, and one or more lumens for fluid communication with the distal and proximal inflatable balloons. The shaft includes one or more infusion ports through the shaft between the distal and proximal inflatable balloons, connected in fluid communication with the one or more infusion lumens to permit infusion of a therapeutic drug or fluid to the isolated portion of the blood vessel being treated. In another presently preferred aspect, one or more perfusion lumens can also be provided in the shaft, with one or more proximal perfusion ports through the shaft proximal to the proximal balloon, and one or more distal perfusion ports distal to the distal inflatable balloon, each of the perfusion ports connected in fluid communication with the one or more perfusion lumens to permit passive perfusion of blood flow between the proximal perfusion ports and the distal perfusion ports to the isolated portion of the blood vessel through each the port between the proximal and distal blocking balloons. In another presently preferred aspect, the shaft further comprises one or more distal infusion ports through the shaft distal to the distal inflatable balloon, connected in fluid communication with the one or more infusion lumens to permit infusion of therapeutic drugs or fluid through the one or more distal infusion ports.
These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings, which illustrate by way of example the features of the invention.